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Results for “MONOPULSE ANTENNA”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

94 GHz integrated horn monopulse antennas

A monolithic azimuthal monopulse antenna for 94 GHz applications has been developed. The structure consists of a single dipole suspended in one plane of an integrated horn cavity to obtain the sum pattern, and an antiparallel pair of dipoles suspended in a different plane of the same horn cavity to achieve the difference pattern. Pattern measurements of microwave models and on the millimeter-wave antennas show good agreement with theory and exhibit symmetry with a sharp -30 dB null at broadside for the difference antenna. Microwave model measurements show input impedances close to 50 Ohms, with greater than -25 dB isolation between sum and difference antennas across a 10 percent bandwidth.

Ling, Curtis C.↗
DOE OSTI2024

Notes on Amplitude versus Phase Comparison Monopulse Antennas for Radar

Monopulse is a technique for determining the Direction of Arrival (DOA) of a radar echo by comparing the simultaneous signal responses from two or more antenna beams or apertures. Two principal architectures are employed: 1) amplitude-comparison monopulse, and 2) phase-comparison monopulse. For a constrained-size fully and uniformly illuminated aperture, there is no meaningful difference between the DOA angle precision achievable by an amplitude monopulse architecture versus a phase monopulse architecture. DOA angle estimation precision is almost exclusively a function of antenna size, operating wavelength, and SNR, regardless of amplitude versus phase monopulse architectures.

47 OTHER INSTRUMENTATION↗
NASA NTRS1974

Variable-beamwidth monopulse antennas

The merits of nine methods for zooming microwave amplitude-sensing monopulse antenna patterns are discussed. Of these, six are directly related to the TDRSS (Tracking Data Relay Satellite System) and are compatible with a deployable-mesh pseudo-paraboloidal main reflector. The remaining three methods utilize radically different geometrical configurations that depart considerably from the TDRSS parameters existing at this time. Preservation of the monopulse postulates is considered to be of prime importance for any variable-beamwidth candidate, however, it is allowed that approximate satisfaction of the postulates should be accepted for practical reasons. All of the methods discussed admit free choice of the polarization state, and the zooming function is never predicated on polarization. Exploration of the zooming techniques was carried out almost entirely by means of the Kirchhoff-Kottler vector diffraction program. The program generates electric and magnetic field intensity, associated phase, and time-average Poynting vector power flow in the intermediate near-field and far-field zones in both receive and transmit modes of operation. A few of the concepts have been verified experimentally with excellent agreement between theory and practice.

Schmidt, R. F.↗
NASA NTRS1993

Microstrip monopulse antenna for land mobile communications

Low cost is one of the main requirements in a communication system suitable for mass production, as it is the case for satellite land mobile communications. Microstrip technology fulfills this requirement which must be supported by a low cost tracking system design. The tradeoff led us to a prototype antenna composed of microstrip patches based on electromechanical closed-loop principle; the design and the results obtained are described.

Garcia, Q.↗
NASA NTRS1996

Ka-band monopulse antenna-pointing systems analysis and simulation

NASA 's Deep Space Network (DSN) has been using both 70-m and 34-m reflector antennas to communicate with spacecraft at S-band (2.3 GHz) and X-band (8.45 GHz). To improve the quality of telecommunication and to meet future mission requirements, JPL has been developing 34-m Ka-band (32-GHz) beam waveguide antennas. Presently, antenna pointing operates in either the open-loop mode with blind pointing using navigation predicts or the closed-loop mode with conical scan (conscan). Pointing accuracy under normal conscan operating conditions is in the neighborhood of 5 mdeg. This is acceptable at S- and X-bands, but not enough at Ka-band. Due to the narrow beamwidth at Ka-band, it is important to improve pointing accuracy significantly (approximately 2 mdeg). Monopulse antenna tracking is one scheme being developed to meet the stringent pointing-accuracy requirement at Ka-band. Other advantages of monopulse tracking include low sensitivity to signal amplitude fluctuations as well as single-pulse processing for acquisition and tracking. This article presents system modeling, signal processing, simulation, and implementation of Ka-band monopulse tracking feed for antennas in NASA/DSN ground stations.

Lo, V. Y.↗
NASA NTRS1996

Ka-Band Monopulse Antenna-Pointing Systems Analysis and Simulation

NASA's Deep Space Network (DSN) has been using both 70-m and 34-m reflector antennas to communicate with spacecraft at S-band (2.3 GHz) and X-band (8.45 GHz). To improve the quality of telecommunication and to meet future mission requirements, JPL has been developing 34-m Ka-band (32-GHz) beamwave guide antennas. Presently, antenna pointing operates in either the open-loop mode with blind pointing using navigation predicts or the closed-loop mode with conical scan (conscan). Pointing accuracy under normal conscan operating conditions is in the neighborhood of 5 mdeg. This is acceptable at S- and X-bands, but not enough at Ka-band. Due to the narrow beamwidth at Ka-band, it is important to improve pointing accuracy significantly (approx. 2 mdeg). Monopulse antenna tracking is one scheme being developed to meet the stringent pointing-accuracy requirement at Ka-band. Other advantages of monopulse tracking include low sensitivity to signal amplitude fluctuations as well as single-pulse processing for acquisition and tracking. This article presents system modeling, signal processing, simulation, and implementation of Ka-band monopulse tracking feed for antennas in NASA/DSN ground stations.

Lo, V. Y.↗
NASA NTRS1974

Design, fabrication, test and delivery of a K-band antenna breadboard model

The results of a research effort to develop a Ku-Band single channel monopulse antenna with significant improvements in efficiency and bandwidth are reported. A single aperture, multimode horn, utilized in a near field Cassegrainian configuration, was the technique selected for achieving the desired efficiency and bandwidth performance. In order to provide wide polarization flexibility, a wire grid, space filter polarizer was developed. A solid state switching network with appropriate driving electronics provides the receive channel sum and difference signal interface with an existing Apollo type tracking electronics subsystem. A full scale breadboard model of the antenna was fabricated and tested. Performance of the model was well within the requirements and goals of the contract.

Source record↗
DOE OSTI2025

Notes on Bayliss Taper for Monopulse Radar

A radar system’s antenna characteristics are fundamental to its performance. A principal defining feature of an antenna’s performance are its often problematic sidelobes. Often in monopulse antenna topologies, the emphasis has been on the sum channel sidelobes at the expense of difference channel sidelobes. Edward Bayliss published a paper detailing a design procedure for managing the difference channel sidelobes. The resulting aperture taper now is identified by his name. This report analyzes his taper derivation, and resulting performance attributes, after which some implementation comments are rendered.

42 ENGINEERING↗